1. Field of the Invention
The present invention pertains to cartons having interfitting cover and bottom portions and in particular to such cartons having an interlocking to prevent or resist separation of the carton portions.
2. Description of the Related Art
Self-locking cartons have been provided in the past to meet a variety of needs. For example, self-locking cartons, having locking cover and bottom portions, are less likely to open unintentionally during shipping, thereby compromising their contents. Further, the locking feature of the carton prevents pilfering or other unauthorized entry into the carton to obtain access to its contents.
To be commercially practical, a self-locking carton should be economical to manufacture, with little or no additional costs in either labor of manufacture or assembly, or in the price or number of components required to produce the locking feature. Further, the self-locking carton should be easy to operate, preferably having an automatic locking engagement.
The following are examples of cartons having locking or coupling features and to which certain improvements, such as those outlined above, can be made. For example, U.S. Pat. No. 2,961,144 discloses a pilfer-proof box consisting of two completely separate, interfitting portions. An upwardly bent tab on the cover portion slides over an outwardly bent tab on the bottom portion of the box, thus providing an interlocking engagement between the two tabs preventing the interfitting box portions from being telescopically separated.
U.S. Pat. No. 2,963,210 has two completely separate interfitting cover and container portions. The cover has an inwardly directed tab received in an aperture formed in the sidewall of the container bottom portion, which restricts separation of the container portions.
U.S. Pat. No. 2,939,624 also has inwardly bent tabs in a cover portion of a container which are received in apertures formed in the sidewalls of a bottom portion of the container. The tabs, when received in the sidewalls prevent telescopic removal of the two container components which, as in the above examples, are separate one from another.
As a further example of this type of coupling arrangement, U.S. Pat. No. 3,734,392 provides a container having separate cover and bottom portions with a locking tab inwardly projecting from the cover and received in an aperture formed in the box sidewall.
The following four U.S. Patents: U.S. Pat. Nos. 2,963,210; 2,939,624; 3,734,392 and 2,961,144 each provide containers having separate but interfittable cover and bottom portions. The cover portions contain an inwardly directed tab received in an aperture of the sidewall of the container bottom portions. When the tab is received in the apertured sidewall, telescopic separation of the cover and bottom portions is prevented.
U.S. Pat. No. 3,713,579 provides a container with a pair of opposed hinged lids, which is suitable for use as a grape lug. Endwalls of the carton bottom portion have upstanding lugs with inwardly facing recesses. Locking tabs carried on the hinged lids are bent in an upward direction and when swung to a closed position are received in the lug recesses to provide a locking feature.
U.S. Pat. Nos. 3,342,401 and 4,717,070 disclose two-part containers with completely separate cover and bottom portions. Tabs on the cover portion are folded or bent so as to protrude into apertures formed in the sidewalls of the bottom portions, thus providing a coupling between the two container portions.
U.S. Pat. Nos. 2,827,222, 3,342,401 and 4,717,070 disclose two-part containers having telescopically interfitting cover and bottom portions.
U.S. Pat. No. 4,076,168 discloses a two-part carton for food products having a variety of interfitting coupling arrangements. For example, button-shaped tabs carried on the cover portion are received in slots formed in the bottom portion sidewalls. In another embodiment, the bottom portion of the container has an outturned rim folded against the sidewall. The cover portion extends below the rim and has an upwardly projecting edge received in the overturned rim portion. In a further embodiment, outwardly directed hook members are received in apertures formed at the lower portions of the container cover and are snapped together to provide a coupling.
U.S. Pat. No. 3,809,305 provides a two-part container having separate cover and bottom portions. The bottom portion has outwardly directed bulging sections which are open or slotted at this bottom end. Inwardly directed tabs carried on an interfitting cover portion are received in the bulging portions of the carton bottom and extend through the open bottom end thereof to provide an inter-coupling.